Installing MacOS on External SSD

Discussion in 'Mac Basics and Help' started by EmmaL20, Nov 23, 2018.


Should I install it normally with APFS? OR Try to install it with HFS?

  1. APFS

    6 vote(s)
  2. HFS

    2 vote(s)
  1. EmmaL20, Nov 23, 2018
    Last edited: Nov 24, 2018

    EmmaL20 macrumors newbie

    Jun 23, 2017
    Hello! I am going to install MacOS on an External SSD and I need some advice.
    1. Should I install it normally with APFS? OR Try to install it with HFS?
    The reason why I am debating over this is because I have heard of APFS having issues like data loss, performance issues, or the fact that it's case-sensitive(?) which broke some apps.

    Currently I am using an iMac with a hard drive that suffers from freezing up or just being very slow. So I thought that this was the best option because I am afraid of breaking my computer if I open it up.

    Also....Any tips on the subject would be appreciated :)

    EDIT: I decided to use APFS because it was easier to setup and here's my review!

    SSD: Samsung T5
    Setup: iMac 2012


    PROs: Everything from the computer boot time, application load time, and file transfers are significantly faster. The computer is also silent now which makes a difference! +Game Install/Download was several times faster on the SSD

    CONs: If you were planning on playing games on it like I was then you'll likely notice the input lag (delay). At first I couldn't tell that it was there but after extended use I noticed that doing simple tasks such as bring up the dock (w/ automatic show & hide setting) would have an input delay that didn't exist on my internal HDD. Another issue is the mouse performance, I am using the Razer Deathadder 2013 and I installed the Synapse drivers (all the restarts and config prompts were done correctly) and yet I still noticed that the performance was worse when compared with the internal HDD.

    Conclusion: Overall it seems like an easy decision for anyone who doesn't play any games on their computer because everything else runs so much better than a traditional HDD! If possible I would recommend installing an SSD internally which I was not brave enough to do.
    • Input Lag (delay)
    • Mouse tracking problems
    If I find a solution to the problem I will come back to this thread. If you have any questions feel free to PM me and I'll try to give you some advice.
  2. ChrisChaval macrumors 6502a


    Aug 30, 2016
    Mojave APFS formatted my external SSD automatically upon installation

    no issues with APFS whatsoever
  3. Audit13 macrumors 601


    Apr 19, 2017
    Toronto, Ontario, Canada
    Installation to an external SSD automatically chose APFS. I'm using APFS on my late 2013 13" Pro and early 2015 Air with no issues.
  4. Fishrrman macrumors P6


    Feb 20, 2009
    You didn't tell us WHICH VERSION of the OS you're looking to install.

    For Mojave, I believe the drive should be formatted to HFS+.
    BUT -- the Mojave installer will automatically convert it to APFS.

    For High Sierra, I -think- the install will depend on how the drive is formatted.
    IF it's HFS+, you end up with an "HFS+ install".
    IF it's APFS, you may end up with an APFS install.
    (Haven't done this for a while).

    Best course of action:
    I would erase the drive to "Mac OS extended with journaling enabled", and then "let the installer do the rest".
  5. mikzn macrumors 65816


    Sep 2, 2013
    Am assuming you are going to install mojave or high sierra on an SSD drive, if so my vote is for APFS.

    I have installed APFS on several MBP's and a a few bootable drives (back ups) and have quite a few older drives with media back ups on HFS+ - all seems to work just fine / no issues

    I migrated my most recent drives and adopted the new file format because (IMHO) sooner or later some features in the new OS's will not be supported on older drives and might as well get on board.

    So far (at least in my case) everything works seamlessly between the 2 formats on different drives.

    Is your current drive a HDD or SSD? that could be the issue with the slowness and freezing?
  6. EmmaL20 thread starter macrumors newbie

    Jun 23, 2017
    Thanks for the advice! My current drive is a HDD so it's very slow.. In the end I decided to install APFS. Everything runs several times better than my internal HDD but I believe there's input lag with my mouse in the software.
  7. chainmailr macrumors member


    Nov 24, 2018
    California, USA
    AFPS isn't case-sensitive by default. It's like HFS+ in that respect. No need to worry about that.

    Data loss: You never know. I trust AFPS enough to use it, but it's true HFS+ has been proven for a longer period of time.
    --- Post Merged, Nov 24, 2018 ---
    macOS since Mavericks has been very slow on HDDs, as if it does way more random reads/writes than before. I don't understand why, but it's unmistakably a disk bottlenecking problem I've seen many times.

    And yes, Apple sells a new iMac with an HDD option. I've used it, and it's pretty slow.

    IDK if there's any reason to use AFPS on an HDD. I'd not bother.
  8. naerct macrumors member


    Mar 19, 2019
    Southern NH

    Neither of your storage situations is good for today's computing. USB3 is very slow despite its improvement over USB2. I see BlackMagic Speed test results in the low 200 MB/s, no matter term how fast the SSD is. With an HDD, it's the other way around where the drive can't go faster than 150 MB/s, but the interior SATA3 is 600MB/s. You have 3 choices. Use Thunderbolt to a single or multiple drive enclosure. Or you can open it up and replace the HDD with an SSD which is pretty easy, or add an SSD and keep the HDD, but that requires a kit and a more difficult installation. I put together a OWC Thunderbay with 4 drives in RAID5 that more than doubles the speeds and gives a 1 drive failure proction. I have also used the same enclosure for adding FAST exterior SSDs with or without RAIDs and more spindle drives to expand storage. The Thunderbolt would be the easiest, but most expensive. It will also be around for your next Mac. Apple offers free RAIDs 1 or 0, while SoftRaid for $180 does all the RAIDs, gives you many more tools, and has worked well for several clients.

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7 November 23, 2018